Houdini 15.5 delivers great production-inspired features both to our established community and our emerging user base. There's a lot more included than in a typical point release, as we've been able to finalize a wide range of features well ahead of our major release schedule.

ModelHoudini has traditionally offered strong procedural modeling sometimes at the expense of its interactive workflow. With improvements made in Houdini 14 and now 15, modellers are now able to work intuitively in the viewport with the new tweak edit workflow, edge sliding, soft selection highlighting and new tools such as PolyBridge and PolyExpand 2D. For working with hi-res models, new retopology tools make it easy to build low-res geometry by drawing right on top of high-res geometry.

RenderRendering in Houdini 15 is faster and richer with improvements to the Mantra renderer such as checkpointing and render view feedback. Shader building has been enhanced with a new shader library, a rebuilt Shader FX 2.0 menu, layered materials and a cartoon shader.Houdini 15 also includes an implementation of Disney's physically-based Principled Shader which is designed to provide artistic flexibility with a minimal set of controls. In addition, a library of royalty-free PBR Ready Textures will be available on sidefx.com for use with Houdini 15's shader building tools.Material stylesheets create a production-level workflow for creating and managing material overrides that work well with Alembic files and packed geometry. Easily set up random textures and variances in material settings to give a unique look to a collection of similar items such as crowd agents.

RenderMan 20RenderMan 20 and RIS shading support is fully integrated into Houdini 15. RIS shaders are available in the RIS Shader Network SHOP and Houdini's VOP context provides a native environment for building RIS shaders with OSL support."Pixar and Side Effects have worked together to create a first class experience for lighters," says Chris Ford, Business Director - RenderMan, Pixar Animation Studios. "Houdini 15 offers interactive shader building tools which make it easy for artists to achieve the look they desire."Houdini 15 comes with a complete set of RenderMan BxDF, Pattern, and Integrator RIS shaders as well RIS light shaders and Camera, Light Probe, and Rolling Shutter RIS projection shaders. There is also a new RIS render node which allows the RIB and RIS render nodes to have cleaner interfaces specific to each mode.

What's new v15.5:

GeometryNewRewrote PolyBevel SOP to do state-of-the-art beveling.Rewrote Polysplit SOP with better interactive insertion of edges and edge loops.Rewrote Dissolve SOP to be more intuitive, faster, and more reliable.Delta Mush deformer smooths arbitrary deformations applied to a polygonal mesh, without smoothing out the detail of the original model.PolyExpand2D now supports variable width offsets and primitive attributes. This is important for road generation and roofing offsets.TopoBuild has new tools for splitting polygons and brushing to move or smooth points.ImprovedBetter/tighter packing of UV islands in the UV Layout SOP.Faster saving of large polygon soups under some conditions, most notably IPR renders.

User experienceNewYou can now copy and paste multiple rows and columns in the Parameter Spreadsheet. You can use this to copy all channel references on a node to another node at once.The viewport now shows displacements for surfaces with a GL Displacement map parameter. See the Open GL ROP and on the Effects tab of the 3D Display options. This feature requires OpenGL 4.0.New option for Euler tumbling in the viewport allows you to tumble the view over the poles.Double-click for edge loop selection.Double-click points or primitives in the viewport to select connected geometry.ImprovedCleaner help layout and improved search.- You can switch the display of lists of items such as HOM methods and environment variables to alphabetical order.- The search now shows "inline" results for nodes, VEX functions, HOM functions/methods, HScript commands and expressions, and common attributes.- A list of categories to the left of search results lets you filter the results quickly.Various handle UI improvements including the display of an outer ring for rotating around the current view axis, the ability to turn off negative axis drawing of translate handles, and the display small draggable translate planes away from the center of the handle. For information, see Using handles.Improvements to the File Chooser.Better geometry snapping, including the ability to snap to X-ray geometry.HOM interface for Flipbooking. For more information see hou.FlipbookSettings.FixedOverlapping multi-selections in Dopesheet and Playbar.

CrowdsNewNew foot planting workflow supported by new parameters on various nodes.Transition graphs let you specify multi-clip transitions at specific frames between agent states.You can now directly import or render FBX characters as agents.Added many new controls to the Crowd State DOP for animation clips, such as options for adjusting the clip and/or locomotion speed, retiming behavior, and allowed speed variance.The new Agent Terrain Adaptation SOP lets you add terrain adaptation to animated agents after a simulation, or use it for simple crowd shots that don't involve simulation.New Agent CHOP imports clips from an agent primitive into CHOPs.New Mocap Biped 3 character on the Character shelf tab. This character has better walk cycles, making it useful to test the new foot-planting features.Houdini now uses vertex normals when deforming agent shapes. This is particularly useful for FBX files, since they typically have vertex normals.Added support for baking additional (non-transform) channels into agents' animation clips. The new Foot Plant CHOP uses this to add channels describing when a foot is planted.ChangedNew versions of the Crowd Solver, Crowd State DOP, Crowd Transition DOP, Crowd Source SOP, Agent Prep SOP, and Agent Terrain Adaptation DOP.The new versions move, rename, and reorganize some parameters to make the behavior of and interaction between the parameters clearer.The Crowd Source SOP is now optional. Any required attributes are initialized by the crowd solver if they don't already exist.Redesigned parameter interface for crowdsAdded support for agents that do not face down +Z and/or are not Y-up.The Agent Configure Joints SOP can now automatically compute initial joint limits from an agent's animation clips.ImprovedCrowd steering behavior, which reduces sliding and spinning for agents.Support for locomotive clips, specifically looping and transitioning between locomotive clips.Usability and robustness of the crowd shelf tools.Terrain adaptation and support for foot locking.Enhanced clip-driven transition controls for crowds.

Lighting and renderingNewVR lens shader, which supports standard projection modes (latlong/cubemap), as well as control over eye separation and eye/neck distance. The Oculus Rift headset is being used to validate the output image format. A Perspective mode has also been added to the shader, to allow rendering of stereo pairs.There is now curvature support for UV Bake. This is done with a new Curvature VOP that provides various properties of surface curvature, such as Gaussian, mean, convexity, concavity, and magnitude. Curvature can be used to add wear to surfaces, and as a control mask for dirt and rust. An output is now available on the VR lens shader for this type of shading.Depth of Field and Motion Blur are now available in the OpenGL ROP.Third party rendering in Houdini Indie.You can now add a Photon modifier property to objects to control how Mantra traces photons through the scene.New UV Triplanar Projection VOP lets you project repeating textures onto geometry easily.SOHO output drivers have a Render to Disk in Background button. This works like all other Render . in Background buttons, requiring a saved .hip file to work properly.ChangedThe Bake Shader has been removed, with the functionality being moved into the VR lens shader. This means that any image plane can be baked, as opposed to be limited to a fixed set of planes.Bake shading controls have been moved from the Bake Texture ROP to standard shaders, which means bake settings can be adjusted on a per-object basis.ImprovedHQueue performance optimizations. The web interface and RPC are significantly more responsive.Optimized tree view picker for the Alembic SOPAlembic ROP's exporting of packed fragment primitives.The point replicate procedural now has an option to unpack the template geometry.FixedYou can now render extra "overscan" image data outside the display window in image formats that support it (for example .pic and .exr). This extra image data may be useful to other software such as Nuke.

Hair, Fur, and GroomingNewYou can now change selections within a single Curve Groom SOP.A Length Scale parameter on the Appearance tab of the Fur Object allows for small post groom adjustments.UDIM support for hair shader textures.Parameter to control which attributes to keep on external guides.Hair shader asset. The hair material in the gallery and the Fur object both use this, so from now on they will be in sync.ImprovedWhen the current object is a fur object or you are inside a fur object, the skin painting tools will use that object without asking for a selection.Restored stroke caching in the Curve Groom SOP.FixedFixed a bug where attributes called "prim" and "primuv" were created on external guides when Snap to Skin was on.Fixed a bug where creating a new Curve Groom node using one of the grooming shelf tools (for example using Ctrl+Click or after selecting a different set of primitives) copied invisible parameters, which could cause cached guide geometry to be transferred to the new SOP.

ScriptingNewYou can now script the creation of flipbooks. See hou.FlipbookSettings.